1. Field of the Invention
This invention relates to a two-wheeled or three-wheeled electrically operated saddle type vehicle. More particularly, to a driving apparatus for an electrically operated saddle type vehicle and to the suspension of an electric motor on a body frame such that it is opposed to a front wheel so that air may be introduced to the electric motor to cool the electric motor.
2. Description of Background Art
An electrically operated saddle type vehicle carries an electric motor and a battery thereon and is driven by supplying power from the battery to the electric motor. In such electrically operated saddle type vehicle, the electric motor and battery both have a certain weight. In addition, the battery has a large volume. Thus, mounting the electric motor and the battery on a body frame is subject to positional restriction.
Conventionally, an electrically operated saddle type vehicle is known wherein a hanger member is suspended on a body frame and a battery is placed at a front portion of the hanger member. An electric motor is placed at a rear portion of the hanger member. The electric motor is disposed such that an output power shaft thereof may be located in a coaxial relationship with a pivot shaft, as disclosed, for example, in the official gazette of Japanese Utility Model Laid-Open Application No. 51-80848.
However, the electrically operated saddle type vehicle of the official gazette of Japanese Utility Model Laid-Open Application No. 51-80848 mentioned above has a problem that, since the battery is located forwardly of the electric motor, the cooling performance for the electric motor is thereby deteriorated.
In addition, an electrically operated vehicle is advantageous in that an electric motor is utilized to drive the driving wheel. Thus, the vehicle does not discharge exhaust gas. Accordingly, the vehicle may be employed in a special environment such as indoors.
However, in a conventional electrically operated vehicle as described in Japanese Utility Model Laid-Open Application No. 51-80848, a high torque is essential for an output of the electric motor and the electric motor must be energized with a high current. Consequently, there is a problem in that the heat generation of the electric motor is high and the electric motor is liable to be thermally fatigued.
As a conventional electrically operated two-wheeled vehicle, a vehicle is known which is disclosed, for example, in the Official Gazette publication of Japanese Utility Model Laid-Open Application No. 51-80848. In the electrically operated two-wheeled vehicle, a driving sprocket wheel is mounted on an output power shaft of an electric motor while a driven sprocket wheel is mounted on a rear wheel. A chain is stretched between the sprocket wheels to interconnect the electric motor and the rear wheel.
However, with the conventional electrically operated two-wheel vehicle described above, in order to change the speed of the vehicle, the speed of rotation of the electric motor must be controlled. There is a problem in that it is difficult to operate the electric motor always in a high efficiency. Thus, a savings in power consumption cannot be achieved.
The problem described above can be solved by assembling a transmission mechanism in operative relationship relative to the electric motor and changing the speed of the output of the electric motor by means of the transmission mechanism. Since an assembly of the electric motor and the transmission mechanism, power unit, is increased in size and also in weight, it is believed that the construction would be difficult.
In a motorcycle of the electric motor driven type, it is common practice that an electric motor serving as a driving source is supported by means of a body frame at a lower portion of the body frame, as described in Japanese Utility Model Laid Open Application No. 51-80848.
However, such a conventional vehicle as described above has a drawback because the electric motor is located at a lower portion of the body near to the ground. The motor is liable to be adversely affected by dust or water from the ground.